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The present invention relates to cervical fixation systems for use with patients with cervical or spinal injuries for immobilizing the neck of the patient to promote healing, and bone screws used with such systems.
Cervical collars are orthopedic devices normally applied by a medical practitioner, such as an orthopedic surgeon or neurosurgeon, for immobilizing the patient to promote healing which often takes many months. Collars immobilize the cervical spine by encasing the neck and chin in a rigid foam or foam lined plastic shell. The immobilization of the chin for extended periods of time can be very uncomfortable making talking, eating and carrying on every day tasks very tedious.
Conventional halo vests are also used to immobilize the patient. However, they are more rigid than the collar. The halos are typically comprised of a vest body having front and rear components for overlying the front and back of the patient""s torso. The front and rear body components of the halo vest are normally secured to one another by flexible straps around the waist and over the shoulders. Halo support rods attach to the upper portions of the body components for supporting a halo that is secured to the patient""s head. The halo is secured by a surgical procedure where four or more pins are driven into the patient""s skull. The pins stay in place by using counter-pressure or opposing pin pressure. Around 8 pounds of pressure is applied to each pin thereby driving the pins into the outer surface of the skull and holding the device in place.
Halos are xe2x80x9coverkillxe2x80x9d. They are too bulky and give patients claustrophobia. They are impossible to sleep in and difficult to maneuver (see U.S. Pat. No. 5,261,873). Several problems exist with the use of halo devices, including infection at the pin sites, loosening of the pins and the resulting movement of the halo, penetration of the skull by the pins, and unwanted loading of the halo caused by the shoulder straps which can be moved if the shoulders are elevated.
It is therefore one object of the present invention to eliminate some or all of the problems associated with known halo and/or collar devices, including having to restrict the chin, loosening problems associated with pins, movement of the device caused by shoulder movement, and bulkiness.
It is a further object of the present invention to reduce the problems associated with the penetration of the skull by pins.
It is still a further object of the present invention to reduce the problems caused by the use of pins in present designs by providing a bone screw compatible with present halo designs.
These and other objects of the invention are achieved in a cervical fixation system that immobilizes the patient""s head and neck to promote healing. The cervical fixation system comprises a body rigidly attached to a patient""s skull at one or more rigid attachment points. In one embodiment, the body comprises a front section and a back section. The front section may be rigidly connected to the back section. In another embodiment, the cervical fixation system comprises a waist belt.
The body of the cervical fixation system is rigidly attached to the patient""s skull. One method of achieving a rigid attachment is through the use of bone screws. The bone screw may comprise a shoulder to prevent penetration of the skull. Additionally, the cervical fixation system may comprise a surface configured to meet a bone screw shoulder. In another embodiment, a spacer may be used to prevent penetration.
The bone screw may also attach to the body of the cervical fixation system. In one embodiment, this is accomplished through the use of a quick disconnect head. In another embodiment, the bone screw comprises threads for attachment to the body.
Additionally, a bone screw is provided that may be used with the present claimed cervical fixation system or existing halo devices. The bone screw engages the patient""s skull for rigid attachment of the cervical fixation system or halo device to the skull. The bone screw may comprise a threaded body configured to engage the cervical fixation system or halo device, and a distal tip threaded to engage the skull. Alternatively, the bone screw may comprise a quick disconnect head for attachment to the cervical fixation system or halo device.
In one embodiment of the bone screw comprising a threaded body, the distal tip diameter is smaller than the threaded body diameter. In a different embodiment, the distal tip diameter and the threaded body diameter are substantially the same, and the bone screw comprises a threaded bushing and a lock bushing. Still another embodiment comprises an integral bushing.